Coulouris was born in Manchester, Lancashire, England, the son of Abigail (née Redfern) and Nicholas Coulouris, a merchant ofGreek origin. He was brought up both in Manchester and nearby Urmston and was educated at Manchester Grammar School. He attended London's Central School of Speech and Drama, in the company of fellow students Laurence Olivier and Peggy Ashcroft.
A major impact on his life was Orson Welles, whom he met in 1936. He joined Welles' Mercury Theatre, and played Mark Antony in their opening modern dress production of Julius Caesar. "Even 'Friends, Romans, countrymen' sounds on his tongue as if it were a rabble-rousing harangue he is uttering for the first time," noted John Mason Brown in the New York Post. In Citizen Kane (1941), Coulouris played Walter Parks Thatcher, a financier similar to J.P. Morgan. George Coulouris won a National Board of Review 'Best Actor' award in 1941 for his performance in Citizen Kane. Orson Welles was the only other Citizen Kane actor to win the same award.
During the 1930s and 1940s he remained a regular figure on the stage and screen, starring in his own Broadway production of Richard III in 1943. His films in this period included For Whom the Bell Tolls (1943), Between Two Worlds (1944), Mr. Skeffington (1944) andWatch on the Rhine (1943), in which he repeated the role he originated in the Broadway play of the same name. He also gave a notable performance as Robert de Baudricourt, in the Technicolor spectacular, Joan of Arc (1948), starring Ingrid Bergman. While most of his performances are strong ones, usually as a heavy or villain, occasionally he could turn his serious characterisations into humorous ones. Thatcher in Citizen Kane is fussy and pompous at times. A better (if briefer) example was in Mr. Skeffington as Dr. Byles, planning to go on a well-deserved, long-delayed holiday only to find it delayed again by a selfish, impossible Fanny Skeffington (Bette Davis).[clarification needed]
Back in Britain
Coulouris returned to Britain after 1950, and appeared in more films, theatre and television productions. His stage work was the most well regarded and included the title role in King Lear at the Glasgow Citizens' Theatre (1952); the lead (Dr. Stockmann) in An Enemy of the People (1959) at the Arts Theatre, Cambridge; Peter Flynn in Sean O'Casey's The Plough and the Stars at the Mermaid Theatre (1962); a part in August Strindberg's The Dance of Death; and Big Daddy in Tennessee Williams's Cat on a Hot Tin Roof (1970).
Later film roles included parts in the Doctor in the House films, Papillon, Mahler, The Long Good Friday and Murder on the Orient Express. During his life he played in over eighty films.
Radio roles were also numerous, and his television roles included parts in Danger Man and The Prisoner episode "Checkmate". Other notable appearances included the reoccurring role; Harcourt Brown in the ABC serials, Pathfinders to Mars and Pathfinders to Venus, which were sequels to earlier serials; Target Luna and Pathfinders in Space. Doctor Who fans would recognize him as Arbitan in the Doctor Who serial The Keys of Marinus.
Coulouris was married to Louise Franklin (1930–1976) and Elizabeth Donaldson (1977–1989) and was the father of computer scientist George Coulouris and artist Mary-Louise Coulouris.
Coulouris died on 25 April 1989, of heart failure following Parkinson's disease in London.